Flow cytometry is an essential resource for investigators performing research in cancer and cancer related areas. With the increasing number of assays being developed which utilize flow cytometry, this resource supports a diverse group of investigators. The Flow Cytometry Core Facility has been used to cycle kinetics, mechanisms of drug action and differences between patient samples and normal donors. The facility has been providing flow cytometry services and technical consultation to Cancer Center members on the Health Sciences Campus and Childrens Hospital Los Angeles for almost 15 years. In the last year, the Facility was utilized by 20 different Cancer members and this usage accounted for 84% of the Facility's total utilization. In addition to the more typical analyses, a significant amount of time was directed to analyzing cells for the expression of specific receptors by the use of tetramers. Another recent application which gained in usage was the study of cellular cytokine activity by intracellular cytokine staining. The general administration and policy making for the Facility is under the direction of David Horwitz, MD. The management of the Facility is performed by Dixon Gray, Ph.D., who also provides technical and scientific support in experimental design and is available to assist investigators in data analysis. The day-to-day operation of the instrument is performed by a full time operator, Mr. Harold Soucier.